#include <stdlib.h>
#include <stdio.h>

#include "mpg123.h"
#include "mpglib.h"

struct mpstr *gmp;

int down_sample;

int (*func_synth)(real *,int,unsigned char *,int *);
int (*func_synth_mono)(real *,unsigned char *,int *);

void set_synth_functions()
{
  typedef int (*func)(real *,int,unsigned char *,int *);
  typedef int (*func_mono)(real *,unsigned char *,int *);

  static func funcs[4] = {
    synth_1to1,
    synth_2to1,
    synth_4to1,
    NULL
    };

  static func_mono funcs_mono[4] = {
    synth_1to1_mono ,
    synth_2to1_mono ,
    synth_4to1_mono ,
    NULL
    };

  func_synth = funcs[down_sample];
  func_synth_mono = funcs_mono[down_sample];
}

BOOL InitMP3(struct mpstr *mp, int dsample)
{
  static int init = 0;

  switch(dsample) {
    case 0:
    case 1: down_sample = 0; break;
    case 2: down_sample = 1; break;
    case 4: down_sample = 2; break;
    default: return 0;
  }

  memset(mp,0,sizeof(struct mpstr));

  mp->framesize = 0;
  mp->fsizeold = -1;
  mp->bsize = 0;
  mp->head = mp->tail = NULL;
  mp->fr.single = -1;
  mp->bsnum = 0;
  mp->synth_bo = 1;

  if(!init) {
    init = 1;
    make_decode_tables(32767);
    set_synth_functions();
    init_layer2();
    init_layer3(SBLIMIT >> down_sample);
  }

  return !0;
}

void ExitMP3(struct mpstr *mp)
{
  struct buf *b,*bn;

  b = mp->tail;
  while(b) {
    if (b->pnt) free(b->pnt);
    bn = b->next;
    if (b) free(b);
    b = bn;
  }
}

static struct buf *addbuf(struct mpstr *mp,char *buf,int size)
{
  struct buf *nbuf;

  nbuf = (struct buf *) malloc( sizeof(struct buf) );
  if(!nbuf) {
    fprintf(stderr,"Out of memory!\n");
    return NULL;
  }
  nbuf->pnt = (unsigned char *) malloc(size);
  if(!nbuf->pnt) {
    free(nbuf);
    return NULL;
  }
  nbuf->size = size;
  memcpy(nbuf->pnt,buf,size);
  nbuf->next = NULL;
  nbuf->prev = mp->head;
  nbuf->pos = 0;

  if(!mp->tail) {
    mp->tail = nbuf;
  }
  else {
    mp->head->next = nbuf;
  }

  mp->head = nbuf;
  mp->bsize += size;

  return nbuf;
}

static void remove_buf(struct mpstr *mp)
{
  struct buf *buf = mp->tail;

  mp->tail = buf->next;
  if(mp->tail)
    mp->tail->prev = NULL;
  else {
    mp->tail = mp->head = NULL;
  }

  free(buf->pnt);
  free(buf);

}

static int read_buf_byte(struct mpstr *mp)
{
  unsigned int b;

  int pos;

  pos = mp->tail->pos;
  while(pos >= mp->tail->size) {
    remove_buf(mp);
    pos = mp->tail->pos;
    if(!mp->tail) {
      fprintf(stderr,"Fatal error!\n");
      exit(1);
    }
  }

  b = mp->tail->pnt[pos];
  mp->bsize--;
  mp->tail->pos++;


  return b;
}

static void read_head(struct mpstr *mp)
{
  unsigned long head;

  head = read_buf_byte(mp);
  head <<= 8;
  head |= read_buf_byte(mp);
  head <<= 8;
  head |= read_buf_byte(mp);
  head <<= 8;
  head |= read_buf_byte(mp);

  mp->header = head;
}

int decodeMP3(struct mpstr *mp,char *in,int isize,char *out,
              int osize,int *done)
{
  int len;

  gmp = mp;

  if(osize < 4608) {
    fprintf(stderr,"To less out space\n");
    return MP3_ERR;
  }

  if(in) {
    if(addbuf(mp,in,isize) == NULL) {
      printf("addbuf error\n");
      return MP3_ERR;
    }
  }

  /* First decode header */
  if(mp->framesize == 0) {
    if(mp->bsize < /*4*/40) {
      return MP3_NEED_MORE;
    }
    read_head(mp);
    if (decode_header(&mp->fr,mp->header) == 0){
      printf("decodeheader error\n");
      return MP3_ERR;
    }
    mp->framesize = mp->fr.framesize;
  }

  if(mp->fr.framesize > mp->bsize)
    return MP3_NEED_MORE;

  wordpointer = mp->bsspace[mp->bsnum] + 512;
  mp->bsnum = (mp->bsnum + 1) & 0x1;
  bitindex = 0;

  len = 0;
  while(len < mp->framesize) {
    int nlen;
    int blen = mp->tail->size - mp->tail->pos;
    if( (mp->framesize - len) <= blen) {
      nlen = mp->framesize-len;
    }
    else {
      nlen = blen;
    }
    memcpy(wordpointer+len,mp->tail->pnt+mp->tail->pos,nlen);
    len += nlen;
    mp->tail->pos += nlen;
    mp->bsize -= nlen;
    if(mp->tail->pos == mp->tail->size) {
      remove_buf(mp);
    }
  }

  *done = 0;
  if(mp->fr.error_protection)
    getbits(16);
  switch(mp->fr.lay) {
    case 1:
#ifdef LAYER1
      do_layer1(&mp->fr,(unsigned char *) out,done);
#else
      printf("layer1 unsupported!\r");
      return MP3_ERR;
#endif
      break;
    case 2:
      do_layer2(&mp->fr,(unsigned char *) out,done);
      break;
    case 3:
      do_layer3(&mp->fr,(unsigned char *) out,done);
      break;
  }

  mp->fsizeold = mp->framesize;
  mp->framesize = 0;

  return MP3_OK;
}

int set_pointer(long backstep)
{
  unsigned char *bsbufold;
  if(gmp->fsizeold < 0 && backstep > 0) {
    return MP3_ERR;
  }
  bsbufold = gmp->bsspace[gmp->bsnum] + 512;
  wordpointer -= backstep;
  if (backstep)
    memcpy(wordpointer,bsbufold+gmp->fsizeold-backstep,backstep);
  bitindex = 0;
  return MP3_OK;
}
